Seat assembly including resilent friction member

ABSTRACT

A damper ( 20 ) for damping motion between two relatively moveable members, such as pivotal motion between components in office chairs ( 10 ). The damper ( 20 ) includes a outer member ( 22 ) having an internal recess ( 23 ) with a inner surface ( 24 ) and a crosswise oriented hole ( 30 ) intersecting the recess ( 23 ), and an inner member assembly ( 32 ) moveable relative to the outer member ( 22 ) having a shaft ( 34 ) with a resilient friction member ( 38 ) mounted thereon. The resilient friction member ( 38 ) frictionally engages the inner surface ( 24 ) in an interference fit relationship thereby radially precompressing the resilient friction member ( 38 ). The resilient friction member ( 38 ) preferably has one or more protrusions ( 40 ) that may be axially or radially oriented.

This is a Divisional Application of U.S. patent application Ser. No.09/349,886, filed Jul. 8, 1999 now U.S. Pat. No. 6,386,528.

FIELD OF THE INVENTION

The invention relates to the area of damping devices. Specifically, itrelates to devices employing a resilient element operable in frictionalcontact with another member for generating damping forces.

BACKGROUND OF THE INVENTION

Various devices are known which utilize resilient elastomer elements toproduce a damping force to control or minimize shock and/or vibration orto generate a locking function. In such prior art devices, the resilientelastomer element is in frictional engagement with another member.

Such devices are, for example, disclosed in U.S. Pat. No. 5,720,369 toThorn entitled “Adjustable, Lockable Devices,” U.S. Pat. No. 5,634,537to Thorn entitled “Locking and Positioning Device,” U.S. Pat. No.5,613,580 to Young entitled “Adjustable, Lockable Strut”, U.S. Pat. No.5,257,680 to Corcoran et al. entitled “Surface Effect Dampers HavingBoth A Hysteresis and A Frictional Component, U.S. Pat. No. 5,183,137 toSiwek et al. “Dual Rate Surface Effect Dampers” U.S. Pat. No. 4,964,516to Thorn entitled “Damped Extended-Motion Strut,” U.S. Pat. No.4,957,279 to Thorn entitled “Fluidless Multi-Directional Motion-DampingMount,” U.S. application Ser. No. 09/040,694 to Thorn et al. entitled“Resistance Generating Device,” and U.S. application Ser. No. 09/040,694to Miller et al. entitled “Elastomer Damper,” all of which are commonlyassigned to the assignee of the present invention.

Although these devices are adequate for their intended purposes, theyeach exhibit certain inadequacies that make them unattractive candidatesfor providing damping forces between relatively moveable members inlow-cost applications. Moreover, many of the devices availableheretofore include large numbers of components and provide dampingforces that may vary significantly with tolerance variations.

Therefore, there is a long felt, and unmet, need for a simple, durable,maintenance free, and cost-effective damper for providing damping forcesbetween relatively moveable members, and in particular, a damperconfiguration which is insensitive to tolerance variations due tomanufacturing processes used to produce it.

SUMMARY OF THE INVENTION

The present invention provides a friction damper of simple constructionincluding a resilient friction element in frictional engagement with asurface of another member. Moreover, the invention provides a damperexhibits excellent tolerance insensitive damping. The damper includes atubular outer member and an inner member assembly reciprocatabletherein. The tubular outer member includes a recess having an innersurface of preferably substantially constant diameter, and a firstattachment hole radially intersecting the recess. The inner memberassembly includes a shaft having a cross-wise directed second attachmenthole and a resilient friction member preferably fixedly mounted (e.g.,by bonding or mechanical fastening means) to the shaft. The resilientfriction member is disposed in the recess in precompressed frictionalcontact with the inner surface of the outer member.

The tubular outer member is preferably open at its first and second endsand the constant diameter is preferably provided along its entire axiallength. The shaft preferably includes a first dimension portion with asmaller dimension portion extending from it. The first dimension portionis preferably integral with the smaller dimension portion.Alternatively, the second portion may be a separate member which engagesthe first.

Various means may be employed for fixedly mounting the resilientfriction member to the shaft. Most preferably, the friction member isbonded to the shaft. Alternatively, the smaller dimension portion mayinclude a deformable portion that is deformed during assembly to securethe resilient friction member onto the shaft. According to anotherembodiment, the smaller dimension portion may include a taper on an endthereof and the shaft may include first and second steps thereon. Duringassembly the resilient friction member is received over the taper andsnaps onto place between the steps. In another embodiment, atinnerman-type lock washer is received over the end of shaft to fixedlysecure the resilient friction member thereon.

As previously mentioned, in several other embodiments, a smallerdimension portion includes a separate member that engages a hole in thefirst dimension portion (e.g., a rivet or fastener). For example, theseparate member may include a thread formed on the smaller dimensionportion that engages a like thread formed on the hole. Moreover, theseparate member may include one or more projections that snap into thefirst portion to retain the friction member in place.

According to a preferred embodiment, the resilient friction memberpreferably comprises at least one protrusion (most preferably aplurality of ribs) formed on an outer surface thereof. The ribs may beaxially or radially oriented. These ribs are precompressed against thesurface and allow significant variations in the tolerances of themembers yet still providing adequate damping forces. Preferably, theresilient friction member is lubricated to provide more consistentdamping and to minimize break away forces. If adjustment to the dampinglevel is desired, one or more o-rings may be received over the resilientfriction member thereby increasing its surface area.

In accordance with another embodiment of the invention, a plurality ofundulations may be formed on the shaft for fixedly securing theresilient friction member to it. The undulations may be corrugations orjagged ridges over which the resilient friction member is received.

The damper according to the invention finds excellent utility fordamping the movement of spring biased seatbacks. Therefore, according toanother aspect of the invention, a tiltable seat assembly is providedwhich comprises a first seat member, a second seat member movablymounted on the first seat member, a spring biasing the second seatmember relative to the first seat member and a damper including aresilient friction member linearly reciprocatable in an outer memberinterconnecting between the first and second seat members.

In more detail, a preferred embodiment of the damper comprises a tubularouter member including first and second open ends, a recess having aninner surface of substantially constant diameter, and a first attachmenthole intersecting the recess at the first end thereof; and an innermember assembly received in the second end having a shaft with a firstportion including a second attachment hole formed therein and a smallerdimension portion extending therefrom, and a resilient friction memberfixedly mounted to the smaller dimension portion, the resilient frictionmember disposed in the recess in frictional contact with the innersurface.

According to another aspect, the invention comprises a tiltable seatassembly having a first seat member, a second seat member movablymounted on the first seat member, a spring biasing the second seatmember relative to the first seat member, and a damper interconnectedbetween the first and second seat members, the damper further comprisinga first member having an engagement surface and attaching to one of thefirst and the second seat members, and a second member linearlyreciprocatable relative to the first member and attaching to the otherof the first and second seat members, the second member including aresilient friction member disposed in frictional contact with theengagement surface wherein the damper provides damping between the firstand second seat members.

It is an advantage of the invention is that it provides a damper withsimple, durable and low-cost construction.

Another advantage of the invention is that it provides adequate dampingforces over relatively broad tolerance ranges.

Yet another advantage of the invention is that it providescost-effective damping for controlling motion in spring-biased chairbackapplications.

The above-mentioned and further features, advantages and characteristicsof the present invention will become apparent from the accompanyingdescriptions of the preferred embodiments and attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings form a part of the specification andillustrate several embodiments of the present invention. The drawingsand description, together, serve to fully explain the invention. In thedrawings,

FIG. 1 is a perspective view of an embodiment of the damper inaccordance with the present invention,

FIG. 2 is a cross sectional view of the damper taken along section line2—2 of FIG. 1,

FIG. 3 is a perspective view of an alternate inner member assembly inaccordance with the present invention,

FIGS. 4-6 are cross sectional side views of other inner memberassemblies in accordance with the present invention,

FIG. 7 is a cross sectional side view of another damper in accordancewith the present invention,

FIG. 8 is a cross sectional side view of another damper includingo-rings for damping augmentation,

FIG. 9 is an end view of an inner member assembly in accordance with thepresent invention including a ribbed resilient friction member,

FIG. 10 is a cross sectional side view of the inner member assemblytaken along line 10—10 of FIG. 9,

FIGS. 11-13 are cross sectional side views of other inner memberassemblies in accordance with the present invention, and

FIG. 14 is a partially sectioned underside view of a tiltable seatassembly in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the Drawings where like numerals denote like elements,FIGS. 1-13 illustrate various embodiments of the damper 20 and innermember assemblies 32 utilized therein. The damper 20 is useful forproviding damping forces between any two relatively-movable structuralmembers. According to the invention, the damper 20 includes an outermember 22 and an inner member assembly 32 linearly reciprocatabletherein.

The outer member 22 preferably comprises a substantially-rigid, tube andincludes a cylindrical recess 23 having an inner surface 24 ofsubstantially constant diameter extending entirely along its length froma first open end 26 to a second open end 28 thereof. A first cross-wiseoriented attachment hole 30 intersects the recess 23 at the first openend 26 of the outer member 22 and is used for pivotally attaching thedamper 20 to a first structural member (see FIG. 14). Preferably, theouter member 22 is manufactured from steel, aluminum or plastic tube.The inner surface 24 preferably includes a smooth finish. Moreover, thesurface 24 may be treated, for example with a Teflon coating to improveits friction and/or wear characteristics. In cases where the outermember 22 is not shown (FIGS. 3-6, 9-13), the various inner memberassemblies 32 depicted are intended to be used with an outer member 22identical to that shown in FIGS. 1-2.

The inner member assembly 32 includes a substantially rigid shaft 34(e.g., plastic (Nylon), steel or aluminum, etc.) having a secondcross-wise oriented attachment hole 36 formed therein, and a resilientfriction member 38 fixedly mounted on the shaft 34. The term “fixedlymounted” means that the member 38 is mounted to the shaft and that itcannot move relative thereto by any appreciable amount, but may moveslightly within bounds. The second hole 36 is used for pivotallyattaching the other end of the damper 20 to a second structural member(see FIG. 14). The assembly 32 is received in the second open end 28 ofthe outer member 22 and is reciprocatable therein. Resilient frictionmember 38 is disposed in the recess 23 in frictional engagement with theinner surface 24 and is preferably radially precompressed such thatthere is always an interference fit between the outer member 22 and theresilient friction member 38.

The shaft 34 preferably includes a first dimension portion 35 with asmaller dimension portion 37 extending axially from it. Except as shownin FIGS. 12 and 13, both portions 35, 37 are generally cylindrical. Mostpreferably, the first dimension portion 35 is formed integrally with thesmaller dimension portion 37 and are manufactured from the samematerial. The resilient friction member 38 is preferably fixedly mountedto the smaller dimension portion 37 of the shaft 34 by a suitablebonding process, for example. The process may include a transfer,injection or compression bonding process, for example, where a suitableadhesive is applied to the smaller portion 37 of shaft 34 as shown inFIG. 2, and elastomer is molded thereto (within a mold) forming theappropriate shape and contours on the resilient member 38. Suchprocesses are known to persons of ordinary skill in the art.Alternatively, the resilient friction member 38 may be molded separatelyin a molding process and subsequently cold bonded to the shaft 34 bycoating the pertinent portions of the shaft 34 with a suitable cold bondadhesive, such as a cyanoacrylate adhesive or the like. In the casewhere the resilient friction member 38 is molded, it includes a throughbore 50 formed therethrough.

Most preferably, as shown in FIGS. 2-6, and 8-13, the resilient frictionmember 38 includes at least one outwardly-extending protrusion 40 formedon a radial outer surface thereof. The at least one formed protrusion 40is in direct frictional contact with the surface 24. Most preferably,the at least one protrusion 40 comprises a plurality of preferablyequally-spaced outwardly projecting ribs formed on an outer surface ofthe resilient friction member 38. For example, as shown in FIGS. 2, 4-6,and 8, the ribs may include a radial orientation and form a corrugatedprofile where each such protrusion 40 is preferably rounded at it'spoint of contact with the surface 24. In each of the illustratedembodiments herein, the resilient friction member 38 may be lubricatedwith an appropriate lubrication, such as a grease. A grease which isfound to be very effective is 3451 or 3452 available from Dow Corning orDamping Nygel available from NYE Lubricants. The valleys formed betweenthe protrusions 40 serve the purpose of carrying and dispersing thelubricant. Suitable resilient materials for the resilient frictionmember 38 comprise Butyl, Silicone, Neoprene, or any other suitableelastomeric materials which are substantially incompressible andelastic. Most preferably, a natural rubber material exhibiting a Shore Adurometer of about 50-60 is found to exhibit the combination ofdesirable characteristics for the damper 20. Alternatively, the rubbermay be internally lubricated with appropriate additives, as is known tothose of ordinary skill in the art.

According to another aspect of the invention, the at least oneprotrusion 40 on the friction member 38 is formed of a plurality of ribsas illustrated in FIGS. 3, 9-11, and 13 that may be axially oriented(generally parallel to the shaft axis). Preferably, the protrusions 40comprise a rectangular, square or trapezoidal profile in radial crosssection. The friction member 38, in these embodiments, may be bondeddirectly to the smaller portion 37 of shaft 34 as shown in FIG. 3, ormechanically locked to the shaft as in FIGS. 9-11 and 13. In both theradially and axially oriented cases, it is preferable that the ribs 40of the resilient member 38 be precompressed radially in the rangebetween about 5% and about 30%, and most preferably about 10%. Thisensures that for normal manufacturing tolerance ranges, the ribs 40 willremains precompressed and adequate damping will be retained.

In the FIGS. 9-10 embodiment for example, the shaft 34 comprises a taper47 at its terminal end over which the resilient friction member 38 isreceived. The shaft 34 also includes a first dimension portion 35 and asmaller dimension portion 37 extending therefrom forming a first step 46at an interface between the portions 35, 37. The taper 47 formed on thesmaller dimension portion 37 terminates at a second step 48. Duringassembly, the resilient friction member 38 is received over the taper 47and snaps onto place on the cylinder of portion 37 between the steps 46,48. Suitable cold bond adhesive may be applied to the shaft 34 prior toassembly to add a secondary means for fixedly mounting the resilientfriction member 38 to the shaft 34. The friction member 38, in thisembodiment, includes a plurality of equally-spaced, radially-directedprojections or ribs 40 which have a rectangular cross section. The shaft34 of the assembly 32, as well as those shown in FIGS. 2, 4, 6, 8 and11-13, is preferably formed from an injection molded plastic such asNylon in an injection molding process as is known to those of ordinaryskill in the art.

In the embodiment of FIG. 11, the mechanical retaining means used tofixedly secure the resilient friction member 38 to the shaft 34comprises a tinnerman lock washer 60. The through bore 50 of resilientfriction member 38 is pressed over smaller dimension portion 37 (whichis slightly larger than it) and the lock washer 60 is received over theportion 37 and is pressed thereon until it snuggly engages the axial endof the friction member 38. The diameter of the washer 60 is preferablyas wide as the diameter of the first portion 35 adjacent to the step 46.The tinnerman washer 60 is of the type that goes on relatively easily,but is extremely difficult to remove thereby permanently securing thefriction member 38 in place against step 46. A taper 47 may be includedon the end of portion 37 to aid in pressing on the friction member 38.

FIG. 13 illustrates another embodiment of inner member assembly 32including a plurality of undulations 58 formed on the smaller portion 37of shaft 34. In this embodiment, the undulations 58 comprise a series ofjagged projections that engage the throughbore 50 of friction member 38.The outer diameters of the jagged portions 58 are slightly larger thanthe diameter of the through bore 50 in its undeformed state such thatthe friction member 38 is received over the shaft portion 37 in aninterference fit relationship. Supplemental cold bond adhesive, asafore-described, may be employed if desired. The jagged portions 58 mayinclude a gentle slope of their onward side and a steep (generallystraight radially outward or even undercut) slope on their backside,such that the friction member 38 is easily pressed on, but once pressedon and positioned to abut the step 46, is very difficult to remove. Asin the previously described embodiment, a taper 47 may be added to theend of shaft portion 37 to aid in pressing on the friction member 38.Other forms of jagged edges may be employed on the shaft 34. Forexample, the jagged ridges may only traverse part way around thecircumference of the shaft 34 or be included only the part of theportion 37 near the end thereof.

FIG. 12 illustrates another embodiment of inner member assembly 32wherein the projections 40 are created by a plurality of undulations 58formed on the smaller portion 37 of shaft 34. Prior to assembly, theresilient friction member 38 comprises an annulus of elastomer. Uponpressed the bore 50 over the portion 37, the member 38 deforms to formthe protrusions 40 and take on the shape shown in FIG. 12. Thisdeformation fixedly secures the sleeve-shaped friction member 38 to theshaft 34. Preferably, the inner dimension of the sleeve 38 in itsundeformed state is slightly smaller than the smallest diameter of theportion 37 thereby ensuring contact along the entire axial length of theshaft portion 37. A taper 47 may be included at the end of portion 37 tohelp facilitate stretching the sleeve 38 over it. Supplemental cold bondadhesive may be employed, if required for the application.

FIGS. 4-7 illustrate various other means for mechanically and fixedlymounting the resilient friction member 38 on the shaft 34 of memberassemblies 32. For example, as illustrated in FIG. 4, the bore 50 offriction member 38 is received over the integral shaft portion 37; theshaft 34 comprising a deformable material such as thermoplastic oraluminum. A washer 62 is received over the deformable shaft portion 37and securely abuts the end of the friction member 38. A tool, utilizingpressure and/or heat, deforms (e.g., crimps) the deformable end portion42. The end portion 42 is deformed such that it retains the washer 62against friction member 38 and the friction member 38 against step 46.

FIG. 5 illustrates a similar assembly 32 as compared to FIG. 4, exceptthe shaft portion 37 comprises a separate member 52 which engages thefirst portion 35. Preferably, the separate member 52 extending from thefirst portion 35 is a rivet. The rivet 64 is received through, andengages, hole 54 formed in the first portion 35 and a head 65 thereofabuts a counter bore 67. The bore 50 of friction member 38 is receivedover the portion 37 and then washer 62 is placed adjacent to its axialend. Upon crimping the deformed end 42 onto washer 62, the frictionmember 38 is securely mounted to shaft 34 and snuggly presses againststep 46.

FIG. 6 illustrates another assembly 32 wherein the shaft portion 37comprises a separate member 52 which engages a hole 54 in the firstportion 35. In particular, the separate member 52 includes one or moreprojections 44 that snap into the first portion 35 to fixedly mount theresilient friction member 38 on the shaft 34. The projection 44 may be aone or more small bumps, a ring, or other interfering projection that iselastically deformed and likewise elastically deform the hole 54 whenpressed therethrough. The bore 50 of friction member 38 is first mountedon portion 37. This subassembly is than pressed far enough inward suchthat the projection(s) 44 reach the counterbore 67. The projections(s)44, upon passing through hole 54, will expand back out and the hole 54will reform to its original shape thereby locking the portion 37, andthus the friction member 38, to the portion 35. A head 68 formed on theportion 37 preferably has a diameter which is at least as large as thediameter of the portion 35 at the step 46 thereby adequately retainingthe member 38. The dimension from the head 68 to the projection(s) 44 issuch that the friction member 38 is securely held in place wheninstalled.

FIG. 7 illustrates another assembly 32 wherein the shaft portion 37 is aportion of a separate member 52. The separate member 52 engages athreaded hole 54 in the first portion 35. In particular, separate member52 is a bolt-like fastener that includes head 68 and a threaded portionthat engages a like threaded portion in the hole 54. The head 68 formedon the portion 37 preferably has a diameter which is at least as largeas the diameter of the portion 35 at the step 46. The resilient frictionmember 38 shown may be an annular sleeve or include axial fibs as shownin the FIG. 3 embodiment. The bore 50 of friction member 38 is receivedover fastener 52 and when the fastener 52 is bottomed in hole 54 theresilient friction member (preferably, a substantially incompressibleelastomer) will bulge radially to assert a radial force against the wall24 of outer member 22 and be secured against both the head 68 and step46. Alternatively, the portions 35, 37 may be devoid of threads and theportion 37 may be ultrasonically welded to the first portion 35 orotherwise secure thereto by an appropriate adhesive. As in all theembodiments herein described, movement of the inner member 32 relativeto the outer member, via applying forces at holes 30, 36, produces adamping force that will retard motion of the members the damper 20 isattached to (see FIG. 14).

FIG. 8 illustrates another embodiment of damper 20 and inner memberassembly 32 therefor. The damping produced by this embodiment isadjustable by one or more o-rings 56 that are received over theresilient friction member 38. The o-rings 56, even when lubricated,remain stationary within the valleys between the ribs 40 and in contactwith the surface 24 of recess 23. The o-rings 56 slide against whenmember 22 when the member 22, 32 move relative to one another. Addingo-rings increases the effective friction area and friction forceobtainable from the damper 20. In this embodiment, the bore 50 offriction member 38 is received over portion 37 extending from integralportion 35 and is preferably fixedly mounted to shaft 34 by suitablecold bond adhesive.

FIG. 14 illustrates the damper 20 of FIGS. 1 and 2 installed in atiltable seat assembly 21. The assembly 21 includes a first seat member25, a second seat member 27 movably mounted (most preferably pivotallymounted about a lateral axis A—A) on the first seat member 25, a spring29 (e.g., a coil spring) biasing the second seat member 27 relative tothe first seat member 25, and a damper 20 pivotally interconnected tothe first 25 and second 27 seat members. The first member 25 may be, forexample, a base that attaches to the underside of a chair's seat frame(not shown) as is known to persons of ordinary skill in the art. Thesecond seat member 27 may be a U-shaped connector which pivotallyattaches at a pivot pin 53 to the first member 25. The seatback uprightmember 31 is secured by threaded knob 51 to the second member 27 and hasthe seatback (not shown) mounted thereon.

The spring 29 is preferably a coil spring including a first end 33 awhich contacts an underside portion of the first member 25, a second end33 b which contacts a portion (the lateral pin 45) of the second member25 and a central portion 33 c which surrounds the pivot pin 53. Thespring 29 is preferably installed in a pretensioned condition and biasesthe second member 27 into a forward position (as shown). Alternatesprings types may be employed, such as elastomer tubeform bushings,torsion springs, plate springs, etc.

The damper 20 according to the invention interconnects between a lateralcylindrical rod 43 of the first member 25 and a lateral cylindrical pin45 of the second member 27; both of which are offset from the pivot pin53. In particular, rod 43 is pivotally received through attachment hole30 and pin 45 is pivotally received through attachment hole 36. A strokelimiter pack 41 formed, for example, from a plurality of stamped platemembers 49 and interspersed washers 78, also attaches between the first25 and second 27 members. A slot 49 formed in each of the plates 49limits the forward and backward strokes of the second 27 relative to thefirst 25 seat member. The slotted first end 41 a of the stroke limiterpack 41 pivotally attaches to a cylindrical lateral rod 43 of the firstmember 25. A second end 41 b of the limiter 41 pivotally attaches to asimilar cylindrical lateral pin 45 of the second member 27. The damper20 damps pivotal motions between the members 25, 27.

The assembly 21 may also include a locking mechanism 72 for locking thesecond member 27 in any intermediate position (end positions determinedby the slot 49) relative to the first member 25. In particular, a coilspring 73 is received over the rod 43 and is precompressed between aninside end of a clevis 74 and a flange 75 of the first member 25. Thisspring 73 axially loads a cylindrical spacer 76 against the limiter pack41 which then snugged against a stationary washer 77 welded to rod 43.This axial loading frictionally locks the members 25, 27 from relativepivotal movement.

In more detail, the washers 78 in the limiter pack 41 are interspersedbetween the plates 79. When the lever 80 (pivotally mounted by pin 81 toclevis 74) is in the position shown, the preload of spring 73 isrelieved, eliminating the axial loading of spacer 76, and enabling achange in position. Rotation of the lever 80 downward (out of the paper)again applies an axial load to spacer 76 thereby frictionally lockingthe washers 78 and plates 79 between the spacer and the stationarywasher 77 and resultantly locking the pack 41. This locks the relativeposition between the members 25, 27, as desired by the user.

In operation (provided the lock mechanism 72 is unengaged), when theuser exerts a force on the seatback upright 31 by leaning back in thechair, the second member 27 pivots downward (out of the paper), loadsthe spring 29, and reciprocates the first member 22 of the damper 20relative to the second member assembly 32. The pin 43 slides in slot 49to the extent of the travel allowed.

The damper 20 is made up of a first member 22 and a second member 32linearly reciprocatable therein. The first member 22 preferablycomprises a cylindrical tube and includes a preferably smooth innerengagement surface 24. The damper 20 is mounted between the rods 43, 45as shown. However, it should be recognized that the orientation may beflipped such that the first member 22 is attached to the second seatmember 27 and the second damper member 32 to the first seat member 25. Aresilient friction member 38, preferably including a plurality ofprotrusions 40, is disposed in frictional contact with the engagementsurface 24 and the damper 20 provides damping between the first 25 andsecond 27 seat members to restrain pivotal motion thereof. The dampingfosters a controlled movement of the seatback in both pivotaldirections. Preferably, a sufficient level of damping force is providedsuch that the damper 20 prevents abrupt forward stops where the pin 43contacts the end of slot 49 in the forward position and provides anadequate damped feel for all motions of the seat back. It should berecognized that although the damper of FIGS. 1 and 2 is illustrated inthe seat assembly 21, that any of the foregoing damper embodimentsillustrated in FIGS. 3-13 may be used as alternatives. Moreover, thedamper may be employed in any seat or other assembly to provide dampingbetween relatively moving components.

In summary, it should be apparent from the foregoing that the presentinvention comprises a novel damper with an outer member and an innermember assembly linearly reciprocatable therein. The assembly includes aresilient friction member received in interference fit relationship withthe housing to generate damping forces therebetween. The inventionprovides a low-cost damper that is simple and robust and particularlyuseful as a damper in tiltable seat assemblies.

While several embodiments including the preferred embodiment of thepresent invention have been described in detail, various modifications,alterations, changes, and adaptations to the aforementioned may be madewithout departing from the scope of the present invention defined in theappended claims. It is intended that all such modifications, alterationsand changes be considered part of the present invention.

What is claimed is:
 1. A tiltable seat assembly comprising: a) a firstseat member, b) a second sear member movably mounted on the first seatmember, c) a spring biasing the second seat member relative to the firstseat member, and d) a damper having a tubular outer member including afirst open end and second open end, a recess having an inner surface ofsubstantially constant diameter extending from the first end to thesecond end; and a first attachment hole radially intersecting the recessat the first end thereof; and an inner member assembly received in thesecond end including a shaft having a first portion of a constantdiameter including a second attachment hole formed radially therethroughand a smaller dimension portion extending from the first portion, and aone-piece resilient friction member including a plurality of protrusionsfixedly mounted to the smaller dimension portion, the one-pieceresilient friction member disposed in the recess in frictional contactwith the inner surface, said damper interconnecting between die firstseat member and the second seat member.
 2. A tiltable seat assemblycomprising: a) a first seat member, b) a second sear member movablymounted on the first seat member, c) a spring biasing the second seermember relative to the first seat member, and d) a damper having atabular outer member including a first open end and second open end, arecess having an inner surface of substantially constant diameterextending from the first end to the second end; and a first attachmenthole radially intersecting the recess at the first end thereof: and aninner member assembly received in the second end including a shafthaving a first portion of a constant diameter including a secondattachment hole formed radially therethrough and a smaller dimensionportion extending from the first portion, and a one-piece resilientfriction member including a plurality of protrusions fixedly mounted tothe smaller dimension portion, the one-piece resilient friction memberdisposed in the recess in frictional contact with the inner surface,wherein the damper provides damping between the first and second seatmembers.
 3. A tiltable seat assembly comprising: a) a first seat member,b) a second seat member pivotally mounted on the first seat member, c) aspring biasing the second seat member relative to the first seat member,and d) a damper having a tubular outer member including a first open endand second open end, a recess having an inner surface of substantiallyconstant diameter extending from the first end to the second end; and afirst attachment hole radially intersecting the recess at the first endthereof; and an inner member assembly received in the second endincluding a shaft having a first portion of a constant diameterincluding a second attachment hole formed radially therethrough and asmaller dimension portion extending from the first portion, and aone-piece resilient friction member including a plurality of protrusionsfixedly mounted to the smaller dimension portion, the one-pieceresilient friction member disposed in the recess in frictional contactwith the inner surface, wherein the damper provides damping between thefirst seal member and the second seat member.
 4. A tiltable seatassembly, comprising: a) a first seat member, b) a second seat memberpivotally mounted to the first seat member, c) a coil spring biasing thesecond seat member to a forward position, and d) a damper having atubular outer member including a first open end and second open end, arecess having an inner surface of substantially constant diameterextending from the first end to the second end; and a first attachmenthole radially intersecting the recess at the first end thereof; and aninner member assembly received in the second end including a shafthaving a first portion of a constant diameter including a secondattachment hole formed radially therethrough and a smaller dimensionportion extending from the first portion, and a one-piece resilientfriction member including a plurality of protrusions fixedly mounted tothe smaller dimension portion, the one-piece resilient friction memberdisposed in the recess in frictional contact with the inner surface,wherein the damper provides frictional damping between the first seatand said second seat members.